The present embodiments relate to ablation planning. In particular, computation of temperature maps is provided.
Ablation is one option for cancer treatment. In spite of recent advances in cancer therapy, treatment of primary and metastatic tumors of the abdomen remains a significant challenge. Hepatocellular carcinoma (HCC) for example is one the most common malignancies encountered throughout the world (e.g., >1 million cases per year). In the U.S. alone, 1 in 153 individuals will develop HCC with reported 5-year survival rates of less than 15%.
For both primary liver cancer and hepatic metastases, liver resection (partial hepatectomy) is the current preferred option in patients having confined disease. In selected cases of early HCC, total hepatectomy with liver transplantation may also be considered. Unfortunately, less than 25% of patients with primary or secondary liver cancer are candidates for resection or transplantation, primarily due to tumor type, location, or underlying liver disease. Consequently, increasing interest has been focused on ablative approaches for the treatment of unresectable liver tumors. Rather than extirpation, this technique uses complete local in situ tumor destruction. A variety of methods have been employed to locally ablate tissue. Radiofrequency ablation (RFA) is the most commonly used, but other techniques are also used, including ethanol injection, cryo-therapy, irreversible electroporation, and microwave ablation.
The RFA procedure is performed by placing a probe within the target area, the tumor, in the liver parenchyma. Electrodes at the tip of the probe create heat, which is conducted into the surrounding tissue, causing coagulative necrosis at temperatures between 50° C. and 100° C. In addition to increasing the number of patients eligible for curative therapy of liver cancer in unresectable patients, local tissue ablation has a significant advantage as ablation may be performed using a minimally invasive approach, including percutaneously and laparoscopically.
To place the probe at the target location, the physician relies on intra-operative imaging techniques, such as ultrasound. However, the success of the procedure depends on the optimal placement of the probe and heat delivery. Different placements may have different results. The success of ablation is further challenged by the hepatic blood vessels that dissipate heat, thus potentially reducing RFA efficiency.